Eye infections have long been a major health problem concern and may be caused by viruses, bacteria, parasites, and fungi which are capable of attacking the surface or the interior of a patient's eye. Infections may more particularly occur as a complication after surgery, which can be particularly devastating for the patient, whether human or animal.
A common form of eye infection experienced by patients is an inflammation of the conjunctiva, which are the membranes of the inner eyelid and the inner corner of the eye's surface. In general, this type of infection is termed “conjunctivitis,” and is commonly referred to as “pink eye.” The inflammation may more specifically affect the eyelid (termed blepharitis) or the cornea (keratitis), among other portions of the eye and surrounding tissue. Conjunctivitis has multiple infectious causes, including bacteria, viruses, and fungi. Non-infectious irritants to the eye, including allergies, foreign bodies entering the eye, and chemical exposure, may also generate the same symptoms.
Conjunctivitis may result in itchiness and pain in one or both eyes, along with a redness or pinkness, and produces an increase in discharges such as tears and pus from the region of the eyeball. These symptoms combine to make the infectious causes of conjunctivitis highly contagious if proper hygiene is not observed, as the infected patient tends to rub their eyes frequently, transferring the discharges—and any infectious agent present—to their hands. The infectious agent can then be spread through direct contact with an infected individual, or exposure to contaminated surfaces touched by the infected individual. The infectious agent may also be transferred to other portions of the patient's body, causing secondary infections to organs and internal tissues. Since newborns habitually contact both their own face and nearby objects, neonatal conjunctivitis is a common concern.
Bacterial conjunctivitis is caused by bacteria which infect the eye through a number of sources of contamination. The most common types of bacteria which cause bacterial conjunctivitis include staphylococcus aureus, haemophilus influenza, streptococcus pneumoniae, and pseudomonas aeruginosa. Gonorrhea and chlamydia may also trigger bacterial conjunctivitis as a complication. Symptoms of the bacterial conjunctivitis generally include a thick eye discharge or pus. Antibiotics have been used to eliminate the bacteria; they are generally applied with topical and antibiotic eye drops or eye ointments.
Viral conjunctivitis is caused by a virus, frequently an adenovirus. Viral conjunctivitis generally produces a watery discharge. Antibiotics are generally not effective against viruses, although they may be used to prevent secondary infections. The common approach to viral conjunctivitis is to treat the symptoms and otherwise let the disease run its course, typically over one or two weeks. This approach is not ideal, due both to the contagious nature of viral conjunctivitis and the present risk of complications; however, past attempts to treat the underlying cause have met with no success in many cases. The field of medicine has generally focused on prevention through methods such as hygiene.
In a related field, surgical prophylaxis is the sterilization of the ocular surface and regions around the eye prior to surgery. Since pathogens and normal ocular flora may enter surgical wounds or infect ocular surface tissues after surgical procedures, surgical prophylaxis is critical to avoiding non-optimal surgical outcomes. However, due to the sensitivity of the eye tissues, a very limited number of sterilizing agents are available that are not intolerable or downright harmful when applied to the eyeball.